Ceratosaurus nasicornis (S/F)

Disambiguation Links Ceratosaurus nasicornis (IDW-JPR)

The “horned reptile,” so named for the distinctive horn on its snout, was discovered in 1883 and the Cleveland Lloyd Dinosaur Quarry of Utah, and was described by Othniel C. Marsh in 1884. Ceratosaurus lived during the Late Jurassic period from about 153 to 148 million years ago; the type species, C. nasicornis, is known only from North America, but specimens of other species have been found in Portugal. Both parts of its binomial name refer to its horn; Ceratosaurus, of course, means “horned reptile,” while nasicornis means “nose horn.”

The type specimen of the dinosaur measures about 5.3 m (17.5 ft) in length, though it is unclear if this animal was fully grown or not; a larger specimen discovered in Utah in the mid-1960s may have been up to 8.7 m (28.8 ft) long. Ceratosaurus had a proportionately large head for the size of its body and small, muscular arms, and osteoderms which ran down its body. In terms of taxonomy, Ceratosaurus belongs to the infraorder Ceratosauria and to the family Ceratosauridae, both of which are named after the animal.

At the end of the 20th century, International Genetic Technologies successfully cloned Ceratosaurus nasicornis on Isla Sorna. During this time, heavy restrictions on genetic engineering were in place through the Gene Guard Act, so the creation of this animal was in violation of the law. It is not known how much control Simon Masrani or Henry Wu had over this activity, or to what degree they were even aware of it.


Ceratosaurus is a medium-sized carnivorous theropod, easily distinguished by its vivid coloration and prominent nasal horn. Adults reach lengths of 30.5 feet and grow to be 12 feet tall, noticeably larger than currently-known fossil specimens. Adults may weigh up to one ton. The skull is large for its body size, and its jaws are lined with a row of long blade-like teeth. When its mouth is closed, most of these teeth are hidden, but ten teeth in the front of the upper jaw protrude out of the mouth. The nasal horn is ridge-like and shaped like an equilateral triangle. It is not very sharp, and is roughly a foot tall in adults; it is much thinner from side to side, located on the midline of the snout. The skull of the animal also has small hornlets above its eyes, and small conical osteoderms on its crown. More elongated osteoderms continue in a row down the midline of the animal’s thick neck and all the way down its back to its tail, located above the neural spines. This feature is unique among theropods known in the fossil record. Its eyes are relatively small, with green sclerae and circular black pupils. The nostrils are somewhat large, likely giving it a good sense of smell.

Detail on the face of an adult Ceratosaurus. Note that ten teeth of the upper jaw remain exposed when the mouth is shut.

The body is overall fairly robust, with a thick neck and stocky chest. Even the tail is thick, tapering down to a small point. The arms are small, with four minute fingers on each hand; the legs are thicker and stronger, with three clawed toes on each foot. Its tail is deep from top to bottom, somewhat like a crocodile’s. Its body is more compact than fleet-footed theropods such as Allosaurus, with shorter legs and a low-built torso.

Coloration of the Ceratosaurus is, perhaps, one of its most striking features. The head is a vibrant shade of red, with some whitish stripes along the upper lips and slightly darker scales around the eyes. Starting around the neck and going all the way to the tail are gray or black irregular stripes, overlaying the animal’s base coloration. These are most vibrant on the neck, becoming gradually more faded toward the tail; they do not extend to the underbelly. The red coloration of the head also fades over the rest of the body, being replaced with a pale yellow color; its underbelly is even lighter, being almost white. On the tail, the gray stripes become closer together, eventually occupying more space than the light yellow base color.

A young Ceratosaurus depicted in Jurassic Park: Builder.

The hatchling and juvenile stages of Ceratosaurus have not yet been observed in the films. A hatchling Ceratosaurus can be created in the mobile game Jurassic Park: Builder, but this may not be indicative of its appearance in the actual film canon. The coloration of the animal in the mobile games also differs significantly from its appearance in the film.

One individual hatched in 1998 or 1999 had reached adulthood by 2001, meaning it grew from infancy to adulthood in two or three years. This was presumably achieved by the use of growth-enhancing supplements provided by Masrani Global Corporation personnel.

Sexual Dimorphism

There is currently no information to distinguish male and female Ceratosaurus. The sex of the animal which appeared in the film is not known.

In Jurassic World: Evolution, specimens of this animal are confirmed to be female and are very similar to the animal which appeared in the film. The Jurassic World Facts mobile application also features a Ceratosaurus similar to the film version and refers to it as female.

Preferred Habitat

As only one individual has been seen so far, the true preferred habitat of this species is not known; it has been sighted in a heavily forested area near a large river affected by tides. In real life, this animal would have inhabited wetlands, lakes, and floodplains.

Jurassic World: Evolution portrays it as preferring 17,700 square meters of grassland with 4,400 square meters of forest within its territory.

Isla Nublar

In late 2004, all surviving Ceratosaurus were transported from Isla Sorna to Isla Nublar. After a few weeks in a quarantine pen, each animal would be introduced to a habitat, presumably in Sector 5 away from the park proper. Population statistics remain unknown between 2004 and 2018. There is no evidence that this animal was ever intended for exhibition in the park.

A report released by the Dinosaur Protection Group on February 4, 2018 indicated that Ceratosaurus had gone extinct on Isla Nublar.

Isla Sorna

Sometime between late 1998 and mid-1999, Ceratosaurus was cloned on Isla Sorna by InGen under its new parent company Masrani Global Corporation. These animals were created in violation of the Gene Guard Act. Within nine months of their creation, they were abandoned to roam the island.

On the night of June 19, 2001, one adult Ceratosaurus was seen on the western bank of Isla Sorna’s central channel. It is not known how many animals, if there were more than one, existed on the island.

Known range of C. nasicornis on Isla Sorna as of June 19, 2001

The interference on Isla Sorna by Masrani Global Corporation caused an ecological collapse over the next five years, and in late 2004, any surviving Ceratosaurus would have been collected and transported to Isla Nublar.


Dinosaur poaching in the Muertes Archipelago and near Isla Nublar was a problem between 1997 and 2018. As there is currently no list of species that are believed to have been poached, it is unknown if Ceratosaurus was among them.

Behavior and Ecology
Daily Activity

Ceratosaurus has been portrayed as being active at night. However, due to a lack of data, its daily activity patterns cannot be stated with confidence.

The mobile game Jurassic Park: Builder portrays Ceratosaurus as being active for 45-minute intervals, whereas this game’s sequel Jurassic World: The Game instead portrays the animal as being active for two-hour intervals.

Diet and Feeding Behavior

While it is known that Ceratosaurus was a carnivore, its diet has not been portrayed, nor have its feeding behaviors. Its blade-like teeth would be capable of inflicting injury to prey, but as the teeth in the very front of the mouth are the largest, it would not likely be able to tear into prey items with its entire mouth. Instead, it would most likely deliver wounding bites and wait for its prey to weaken.

In real life, Ceratosaurus is believed to have lived near bodies of water and may have been a skilled swimmer. This would allow it to prey on fish, turtles, and other aquatic life. On Isla Sorna, the river where this dinosaur was sighted was home to fish such as bonitos. The mobile game Jurassic Park: Builder describes this animal as being an excellent swimmer which feeds on fish and marine reptiles.

Video games have consistently portrayed it as feeding primarily on small to medium animals and carrion, as well as displaying cannibalistic tendencies in Jurassic Park: Operation Genesis. This game identifies the Ceratosaurus as being a generalist feeder, not being picky about its diet (though the game states that its favored prey is Dryosaurus, a species which was not cloned in the films). They are portrayed in the game as being capable of hunting in groups, but also solitary hunting. It is portrayed in Jurassic World: Evolution as having a large appetite for its size.

According to the Jurassic World Facts mobile application, Ceratosaurus is not a powerful biter, but can run relatively fast. This suggests that it tires out terrestrial prey through chasing rather than ambushing with a strong biting attack.

Social Behavior

Only one member of this species has been seen, so no confident conclusions about its social behavior can be made. However, the individual seen was solitary.

Its physical features indicate that it does engage in some degree of social interaction, as its striking pattern would make it poor at camouflaging and its nasal horn is not robust enough to serve any combative purpose.

The game Jurassic Park: Operation Genesis portrayed the animal as comfortable in small to medium groups, but without strong social instincts and a tendency toward cannibalism. Groups are portrayed hunting together when prey is available. This game’s spiritual sequel, Jurassic World: Evolution, portrayed the animal as being less social; it becomes stressed in groups of more than three, and as in the original game, it rarely socializes with others of its kind.


As a dinosaur, this animal would lay eggs to reproduce. However, specific details about its reproductive behaviors are unknown. Its nasal horn, bright facial coloration, and elongated spinal osteoderms all indicate that it would engage in some kind of display behavior, but the nature of such behaviors are unknown. Other theropods are portrayed as having cloacae in Jurassic Park: The Game, but details about the reproductive anatomy of Ceratosaurus have not been disclosed.


Ceratosaurus has been heard to make low growling or gurgling noises when alone, and was heard making a groaning sound when frightened.

The video game Jurassic World: Evolution gives it a range of loud roars which it uses to confront rivals and establish territory.

Ecological Interactions
Ceratosaurus displaying a fear response

While there is a lack of behavioral data on this animal, it is known to share some overlapping territory with the much larger Spinosaurus. On one occasion, it smelled dung from this carnivore and immediately retreated from the area, suggesting an antagonistic relationship between this animal and its larger, stronger, and more aggressive neighbor.

As with nearly all de-extinct species, InGen’s ability to extract its DNA would be reliant on the fact that hematophagous, or blood-drinking, parasites such as female mosquitoes fed upon the blood of this animal. It is not known whether hematophagous species from the modern day still use it as a host.

Jurassic Park: Operation Genesis portrays the Ceratosaurus as being aggressive, but mostly when hungry; it will tolerate smaller carnivores in its territory so long as they do not compete with it for prey. However, it will flee larger carnivores. In the game, this animal can be seen allowing small carnivores to feed from carcasses of prey it has killed.

The video game Jurassic World: Evolution portrays it as preferring a solitary life with few other species nearby. It is a host to the bacterium Campylobacter, which can sometimes cause the animal to become sick with campylobacteriosis. This bacterium is common in modern birds, inhabiting up to 100% of some poultry in real life.

Interactions with Humans

Ceratosaurus is, perhaps, one of the least aggressive and most docile carnivorous dinosaurs. It has only been recorded interacting with humans once in the films, on which occasion it investigated a small group of humans including Dr. Alan Grant, Paul Kirby, and Amanda Kirby. The animal showed no signs of aggression, sniffed them, and retreated into the forest upon smelling Spinosaurus dung on them. It has been suggested that it was discouraged from eating them by the smell, but during the encounter it did not make any attempt to attack; instead, the animal simply appeared to be curious.

Its existence was of concern to Masrani Global Corporation, as it was not on InGen’s species list and therefore was substantial evidence that InGen had violated the Gene Guard Act. The survivors of the incident on Isla Sorna in 2001 were silenced from speaking about this animal’s existence following their rescue. Specimens were relocated to Isla Nublar in 2004, where they were ostensibly held as future attractions; however, it is not known whether they were ever exhibited in the park. They are absent from the official Jurassic World website, along with other animals which were known to be on the island but not on exhibition. Therefore, it is most likely that Ceratosaurus was never placed in a park attraction.

Along with three other genera of dinosaur, Ceratosaurus was used as evidence during the 2016 investigation by the United States Congress into violation of the Gene Guard Act by InGen. An anonymous hacker revealed in late 2015 during the inquiry into Jurassic World that these four dinosaur genera were created illegally between 1998 and 1999, and three months later, the US Congress announced that it was open to inquiry into violation of the Gene Guard Act.

The video game Jurassic Park: Operation Genesis and its sequel Jurassic World: Evolution both portray the Ceratosaurus as a more aggressive hunter which will prey on humans if they are available.

Behind the Scenes

It was originally thought that the CGI model of the Ceratosaurus resembled that of the Tyrannosaurus, and as a result the Ceratosaurus was actually considered to be a mutant by the majority of the Jurassic Park fandom. It was classified as Ceratosaurus “mutatus” (x Tyrannosaurus); it was inferred that InGen may have filled in the gaps in the Ceratosaurus genome with tyrannosaur DNA. However, this was entirely speculative and is considered inaccurate now, as the Ceratosaurus from the Jurassic Park /// dinosaur charts show that this line of thought was wrong. We are therefore left to believe that it is, indeed, Ceratosaurus nasicornis that is present on Isla Sorna with no clear indications that it was a mutated species or not.

In the original script for the film, the characters would have encountered a Carnotaurus during this scene instead. Unlike the Ceratosaurus, this animal acted aggressively toward the humans and was only repelled by the smell of spinosaur dung.